Computer server systems in modern data centers are commonly mounted in specific configurations on server racks for which a number of computing modules, such as server trays, server chassis, server sleds, server blades, etc., are positioned and stacked relative on top of each other within the server racks. Rack mounted systems allow for vertical arrangement of the computing modules to use space efficiently. Generally, each computing module can slide into and out of the server rack, and various cables such as input/output (TO) cables, network cables, power cables, etc., connect to the computing modules at the front or rear of the rack. Each computing module contains one or more computer servers or may hold one or more computer server components. For example computing modules includes hardware circuitry for processing, storage, network controllers, disk drives, cable ports, power supplies, etc.
Power in a computer system is commonly managed on multiple levels. In a datacenter, for example, the total power allotted to the entire datacenter may fluctuate according to time-varying energy costs. The power allotted to the datacenter may be subdivided among multiple racks and among the rack-mounted chassis in the datacenter.
The power consumed by a server system represents a significant portion of the operational cost of that server system. The cost of powering a server system represents a significant portion of the overall ownership expense. Such costs are particularly sizeable in a datacenter, which may include as many as tens of hundreds of high-power, rack-mounted servers mounted in multiple, high-density chassis or racks. Therefore, power management is an important consideration in the design, development, and operation of computer systems.